THE ROVER SD1 FORUM

Count · SD1 User Joined: 13 Sep 2007 Posts: 8 Location: Finland

Hi all,
I've got a -83 V8 VDP and the trip computer doesn't show anything except zeroes for fuel consumption. How it's supposed to work, as the car is a carb version and not EFI? I've got the Haynes book but that doesn't really tell anything about the sensors etc. so I'd hazard a guess that there must be two sensors, one for the line going to the carbs and another for the return. How does one figure out which is faulty?

I'm thinking about putting an EFI to the car, so it would be appreciated if someone could tell what's been done differently in the EFI, if anything.

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-79 Range Rover V8
-83 SD1 VDP V8

Count · SD1 User Joined: 13 Sep 2007 Posts: 8 Location: Finland

5000SE wrote:

I'm not an expert - I think somebody like Ramon Alban will be able to advise more - but for MPG calcs the computer will use fuel low and speed, so if you're not getting anything, the pulses from the speedo transducer may be the problem rather than from your fuel flow transducer.

I _think_ that the speedo works, even though I haven't driven the car other than taking it down from the trailer and around the garage, so the speed sensor should be OK. But doesn't the SD1 have a fuel return line? The Haynes isn't exactly clear on that, but what I remember from dismantling my -75 Rangie it did have a return line. I once test drove a VDP for sale which did have a working trip computer but I don't recall if it showed anything when the car wasn't moving.

Thank you, now I have something to think about over the weekend Smile

_________________
-79 Range Rover V8
-83 SD1 VDP V8

Lehto · Posted: Thu Sep 13, 2007 3:38 pm Post subject:

Theres no fuel return lines in the carburated model. And if there is... I didnt seem to find any when I took my car apart.

There should be some wires running on the intake manifold. Check that corrision hasnt eaten the connectors. Good squirt of penetration oil (and no... not what they sell at sex shop!) in the connectors and then plug it in back and forth few times and try again? I didnt check if my one worked because that was last thing on my mind.

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Owner of 3 Rovers and 1 MG.

Chris P · Posted: Thu Sep 13, 2007 4:00 pm Post subject:

The fuel consumption trip works off a flow meter for the carb engine. For EFi, a
black box of tricks takes the feed from no. 8 injector and emulates the flowmeter
of the carb (as fuel burn rate is proportional to injector 'open' time).

If you are expecting to see fuel consumption at rest, you won't. The trip computer
only shows imperial/federal MPG or litres/100km - not litres/hr you see on modern
trip computers. At rest, it'll show 0.0.

Lehto · Posted: Thu Sep 13, 2007 6:19 pm Post subject:

the "modern" computers dont always show it either. None of the jaguars ive seen (latest being 2007 XK8) have showed the litres / hour values. Only car with that i have seen was a opel meriva Very Happy

_________________
Owner of 3 Rovers and 1 MG.

Count · SD1 User Joined: 13 Sep 2007 Posts: 8 Location: Finland

Chris P wrote:

The fuel consumption trip works off a flow meter for the carb engine. For EFi, a
black box of tricks takes the feed from no. 8 injector and emulates the flowmeter
of the carb (as fuel burn rate is proportional to injector 'open' time).

If you are expecting to see fuel consumption at rest, you won't. The trip computer
only shows imperial/federal MPG or litres/100km - not litres/hr you see on modern
trip computers. At rest, it'll show 0.0.

OK Chris, that helps a lot. There's enough to be fixed that I don't necessarily want to touch anything which isn't broken. Is the trick box included in the std EFI ECU or is it a standalone piece?

_________________
-79 Range Rover V8
-83 SD1 VDP V8

Chris P · Posted: Thu Sep 13, 2007 7:16 pm Post subject:

Lehto wrote:

the "modern" computers dont always show it either. None of the jaguars ive seen (latest being 2007 XK8) have showed the litres / hour values. Only car with that i have seen was a opel meriva Very Happy

Maybe it's a GM thing then. I don't drive much other than my SD1, but
I did drive a Holden Monaro last year in Australia - that gave l/hr fuel
when at rest.

Chris P · Posted: Thu Sep 13, 2007 7:18 pm Post subject:

Count wrote:

OK Chris, that helps a lot. There's enough to be fixed that I don't necessarily want to touch anything which isn't broken. Is the trick box included in the std EFI ECU or is it a standalone piece?

The box is behind the dash, it just takes a feed from no. 8 injector from
the ECU - it's a small black box, about the size of two relays.

D131OVP · Posted: Tue Oct 23, 2007 4:53 pm Post subject:

Chris P wrote:

Count wrote:

OK Chris, that helps a lot. There's enough to be fixed that I don't necessarily want to touch anything which isn't broken. Is the trick box included in the std EFI ECU or is it a standalone piece?

The box is behind the dash, it just takes a feed from no. 8 injector from
the ECU - it's a small black box, about the size of two relays.

Is that behind the instruments or behind the dash proper?

_________________
4.5, TP, 45mm inlets, big heads - just not all in the car at the moment...

Chris P · Posted: Tue Oct 23, 2007 6:44 pm Post subject:

D131OVP wrote:

Chris P wrote:

Count wrote:

OK Chris, that helps a lot. There's enough to be fixed that I don't necessarily want to touch anything which isn't broken. Is the trick box included in the std EFI ECU or is it a standalone piece?

The box is behind the dash, it just takes a feed from no. 8 injector from
the ECU - it's a small black box, about the size of two relays.

Is that behind the instruments or behind the dash proper?

Behind the instruments, i.e. under the binnacle cover. It's just to the
right of the trip computer.

The trip computer interface is totally separate to the EFi ECU.